Challenges When Quantifying Arctic Ecosystems

Quantifying diversity and abundance of arctic aquatic organisms adds additional challenges to those typically encountered during surveys of southern ecosystems. Knowledge of species presence, distribution, and abundance is typically limited. Survey design for direct (e.g., nets) and indirect (e.g., acoustics) sampling technologies may be constrained by ice, ignorance of local bathymetry, and lack of supporting infrastructure. A recent survey in the Beaufort Sea is used to illustrate challenges in Arctic system studies. Minerals Management Services (MMS) requested a survey of the fish community to use as a baseline for potential affects of oil and gas exploration and drilling. The request was expanded to an ecosystem survey including demersal and pelagic fish, zooplankton, benthic invertebrates, and water column properties. Sampling consisted of seven acoustic transects spaced 10 nmi apart, 25 bottom trawl stations along transects in three depth strata, and 28 midwater trawls for species identification and length frequency distributions. Oceanographic, zooplankton, and benthic invertebrate samples were obtained at trawl stations. Marine mammal and seabirds were counted during transit to the survey site and during acoustic transects. Of the 34 identified fish species, Arctic cod (Boreogadus saida) was the dominant fish observed in the pelagic and benthic communities. A total of 174 invertebrate species were identified comprising 94% of the total bottom trawl catch weight. Commercial-sized snow crab (Chionocetes opilio) was observed in the Arctic for the first time. Six fish and two invertebrate species were previously unreported but before community composition changes can be attributed to climate affects, the survey area must be expanded over space and time. Full ecosystem monitoring requires inclusion of apex predator interactions with lower trophic levels.